Getting Started with an AppExpert Application

1. Getting Started with an AppExpertApplication

2. Public Endpoint • The IP address and port combination at which the NetScaler appliance receives client requests for the associated web application. • A public endpoint can be configured to receive either HTTP or secure HTTP (HTTPS) traffic. • All client requests for the web application must be sent to a public endpoint. • An AppExpert application can be assigned multiple endpoints. • You configure public endpoints after you import a template.

3. Application Unit • An AppExpert application entity that processes a subset of web application traffic and load balances a set of services that host the associated content. • The subset of traffic that an application unit must manage is defined by a rule. • Each application unit also defines its own set of traffic optimization and security policies for the requests and responses that it manages. • The NetScaler services associated with these policies are Compression, Caching, Rewrite, Filter, Responder, and Application Firewall.

4. Application Unit • By default, every AppExpert application with at least one application unit includes a default application unit, which cannot be deleted. • The default application unit is not associated with a rule for identifying requests and is always placed last in the order of application units. • It defines a set of policies for processing any request that does not match the rules that are configured for the other application units, thereby ensuring that all client requests are processed. • Application units and their associated rules, policies, and actions are included in AppExpert application templates.

5. Service • The combination of the IP address of the server that hosts the web application instance and the port to which the application is mapped on the server, in the format <IP address>:<Port>. • A web application that serves a large number of requests is usually hosted on multiple servers. • Each server is said to host an instance of the web application, and each such instance of the web application is represented by a service on the NetScaler appliance. • Services are deployment-specific, and are therefore not included in templates. • You must configure services after you import a template.

6. Application Unit Rule • Either a classic expression or a default syntax expression that defines the characteristics of a traffic subset for an application unit. • The following example rule is a default syntax expression that identifies a traffic subset that consists of four image types: HTTP.REQ.URL.SUFFIX.EQ("bmp") || HTTP.REQ.URL.SUFFIX.EQ("gif") || HTTP.REQ.URL.SUFFIX.EQ("png") || HTTP.REQ.URL.SUFFIX.EQ("jpg")

7. Traffic Subset • A set of client requests that require a common set of traffic optimization and security policies. • A traffic subset is managed by an application unit and is defined by a rule.

8. Getting Started with an AppExpertApplication • The process of setting up an AppExpert application begins with downloading the appropriate AppExpert application template from the Citrix Community Web site: http://community.citrix.com/display/ns/AppExpert+Templates • The template that you need depends on the NetScaler release running on your appliance

9. Getting Started with an AppExpertApplication • After you download the template, you must import the template to the NetScaler appliance, configure deployment settings, and then verify the configuration to make sure that the AppExpert application is working as expected • You can either import the template file directly from your local computer or upload the template to the appliance and then import it.

10. Getting Started with an AppExpertApplication • During import, along with the template file that you specify in the AppExpert Template Wizard, you can include a deployment file that contains deployment details. • If you choose to include a deployment file, you do not have to provide any additional information. • All application-configuration information is imported from the template file and all deployment-specific information for the application is imported from the deployment file.

11. Getting Started with an AppExpertApplication • The NetScaler appliance imports all configuration settings from the deployment file through the NITRO API and the wizard displays the configuration summary screen for your verification. • If you do not include a deployment file, the wizard displays screens on which you can specify deployment information. • During import, if an error occurs, the configuration changes that were made during the import process are automatically rolled back.

12. How an AppExpert Application Works • When the endpoint receives a client request, the NetScaler appliance evaluates the request against the rule that is configured for the topmost application unit. • If the request satisfies this rule, the request is processed by the policies that are configured for the application unit, and then forwarded to a service. • The choice of service depends on which services are configured for the application, and on settings such as the load balancing algorithm and persistence method configured for the application unit.

13. How an AppExpert Application Works • If the request does not satisfy the rule, the request is evaluated against the rule for the next topmost application unit. • In this order, the request is evaluated against each application unit rule until the request satisfies a rule. • If the request does not satisfy any of the configured rules, it is processed by the default application unit, which is always the last application unit.

14. How an AppExpert Application Works • You can configure multiple public endpoints for an AppExpert application. • In such a configuration, by default, each application unit processes requests received by all the public endpoints and load balances all the services that are configured for the application. • However, you can specify that an application unit processes traffic from only a subset of the public endpoints and load balances only a subset of the services that are configured for the AppExpert application.